1. Field of the Invention
The present invention relates to a resist pattern thickening material that enables formation of a fine space pattern by thickening a resist pattern formed upon manufacturing of a semiconductor device, while exceeding the exposure (resolution) limits of the light sources of available exposure devices, to a process for forming a resist pattern, to a semiconductor device, and to a method for manufacturing the semiconductor device, by utilizing the resist pattern thickening material.
2. Description of the Related Art
In recent years the increase in the packing density of semiconductor integrated circuits has put LSIs and VLSIs to practical use. In keeping with this trend, interconnection patterns are downsized to as small as 200 nm or less, with the smallest ones reaching even as small as 100 nm or less. A lithographic technique is extremely important to achieve formation of fine interconnection patterns; with this lithographic technique a substrate is coated with a resist film, selectively exposed to light, and developed to form a resist pattern. Dry etching is then performed for the substrate using the resist pattern as a mask, and the resist pattern is removed to provide a desired pattern (e.g., an interconnection pattern). The lithographic technique, however, requires that exposure light (light used for exposure) have a short wavelength and that high-resolution resist materials tailored to the characteristics of the exposure light be developed.
However, reducing the wavelength of exposure light requires improvement of exposure devices, which requires a great deal of cost. Further, the development of new resist materials suitable for exposure light of shorter wavelength is not easy.
To overcome these problems, a technique has been proposed in which a fine pattern is formed by using a resist pattern thickening material (hereinafter referred to as “resist swelling agent” in some cases) by which a resist pattern made of conventional resist material is thickened and thus a fine space pattern can be obtained. For instance, Japanese Patent Application Laid-Open (JP-A) No. 10-73927 discloses a technique called RELACS. According to the disclosure, a KrF resist pattern is formed by exposing a KrF (krypton fluoride) resist film to KrF (krypton fluoride) excimer laser light of 248 nm wavelength which is deep ultraviolet light. Thereafter, the KrF resist pattern is covered with a water-soluble resin composition to form a coated film. The coated film and KrF resist pattern are then made to interact with each other at their interface with help of acid remaining in the KrF resist pattern material, so that the KrF resist pattern is thickened (hereinafter this process is referred to as “swelling” in some cases). In this way the distance between adjacent lines of the KrF resist pattern is shortened, enabling the formation of a fine space pattern. Subsequently, a desired pattern (e.g. an interconnection pattern) with the same shape as the space pattern is formed.
The RELACS technique, however, has the following problems: The KrF resist to be used is formed of an aromatic resin composition such as novolac resin and naphthoquinonediazide resin, and therefore, while aromatic rings contained in the aromatic resin composition allows KrF excimer laser light (wavelength: 248 nm) to pass through it, they absorb ArF (argon fluoride) excimer laser light (wavelength: 193 nm), which has a shorter wavelength than KrF excimer laser light, thereby preventing it from passing through the aromatic resin composition. For this reason, when the KrF resist is used, it is impossible to use ArF excimer laser light as exposure light and to form, for example, a fine interconnection pattern. Moreover, the RELACS technique also has a problem that although the resist swelling material is effective for thickening or swelling of the KrF resist, it is not suitable for thickening or swelling of the ArF resist. In addition, the resist swelling agent itself has poor etching resistance. Thus, if the ArF resist pattern, which has poor etching resistance, is intended to be thickened (swelled), it is impossible to form a pattern with the same shape as the swelled pattern on the substrate. Even when the KrF resist pattern, which has relatively excellent etching resistance, is intended to be thickened (swelled), it is impossible to perform precise etching in a case where, for example, the etching conditions are stringent, where the substrate is thick, where the KrF resist pattern is fine, and where a resist film is thin, leading to the problem that a pattern with the same shape as the swelled pattern cannot be obtained.
From the standpoint of forming fine interconnection patterns, it is desirable to use exposure light of wavelength shorter than the wavelength of KrF excimer laser light (wavelength of 248 nm), such as ArF excimer laser light (wavelength of 193 nm). When x-ray or electron beam having a wavelength shorter than ArF excimer laser light is used for pattern forming, however, it results in high cost and low productivity. Thus, the utilization of ArF excimer laser light is desired.
Accordingly, the present inventors have proposed a resist pattern thickening material capable of forming a finer ArF resist pattern by improving, using a surfactant, its compatibility with an ArF resist pattern on which the resist swelling agent cannot work effectively by the RELACS technique (see Japanese Patent Application Laid-Open (JP-A) No. 2004-126080). The use of this resist pattern thickening material composition, however, sometimes causes pattern size reduction to depend on the pattern size before thickened—the larger the pattern size before thickened, the more the amount the pattern size decreases by a thickening treatment.
Thus, a technology that can use ArF excimer laser light as exposure light in a patterning process, can sufficiently thicken an ArF resist pattern or the like to an extent that has never been achieved by the RELACS technique using the resist swelling agent, and can achieve easy, low cost formation of a finer space pattern or interconnection pattern, has yet to be provided.
It is an object of the present invention to solve the foregoing problems and to achieve the objects described below.
An object of the present invention is to provide a resist pattern thickening material, which can utilize ArF excimer laser light as exposure light in a patterning process; which, when applied over a resist pattern such as a line-space pattern, can uniformly and stably thicken the resist pattern regardless of the composition or size of the resist material while reducing the roughness of the surface thereof; which has excellent etching resistance; and which can achieve easy, efficient, and low cost formation of fine space patterns, exceeding the exposure (resolution) limits of the light source of an exposure device.
Another object of the present invention is to provide a process for forming a resist pattern, which can utilize ArF excimer laser light as exposure light in a patterning process; which can uniformly and stably thicken a resist pattern such as line-space pattern regardless of the composition or size of the resist material while reducing the roughness of the surface thereof; and which can achieve easy, efficient, and low cost formation of fine space patterns, exceeding the exposure (resolution) limits of the light source of an exposure device.
Still another object of the present invention is to provide a process for manufacturing a semiconductor device, which can utilize ArF excimer laser light as exposure light in a patterning process; which can form fine space patterns, exceeding the exposure (resolution) limits of the light source of an exposure device; and which can efficiently mass produce high-performance semiconductor devices having a fine interconnection pattern formed using the space pattern; and a high-performance semiconductor device having a fine interconnection, manufactured by the process for manufacturing a semiconductor device.